Background: Prior Art
Cardinal Directions
Older directional names appear for the four cardinal directions originating from a North and South wind axis and a dawn to dusk axis.
The Twelve Classical Wind Directions
Elaboration and refinement of the cardinal directions with intercardinal directions produced eight directions, then extended to twelve by philosophers. Classically in Greek and later in Latin, the twelve directions were named by winds blowing from those directions. These were:
Adaptation of these wind directions was proposed for the orienteering directions as of magnetic compasses or to be shown on maps. However, while the resulting angles of these directions may be approximately consistent with dozenal division of the circle at the latitudes in which the Mediterranean civilisations sailed, the directions of the rising and setting points at the horizon of a celestial body such as the sun on the ecliptic vary with latitude.
Binary division of directions
More recent compasses from medieval times have been based on successive bisections of the angles between cardinal directions, as for example on portolan maps. The names of the resulting eight principal wind directions were:
Compass directions by explorers from Iberia may have been influenced by Islamic navigators.
Astronomically derived angular measure of direction
By rising and setting points on the horizon
It was shown in the table above of the twelve classical wind directions how the solar rising and setting points on the horizon could have been used to determine intercardinal directions.
The principle of celestial rising and setting directions could be extended from the sun, which changes during the year, to the fixed stars, which have the same rising and setting points all year round. However, the directions of rising and setting of the fixed stars still vary with latitude and furthermore their declinations alter over generations due to precession, causing the celestial systems which were once used to be now obsolete.
I found it surprising that the binary compass directions were assigned by the Muslims to fixed stars roughly according to their declinations, even though declination is a polar angle, measured between the pole and equator, whereas the compass direction is an azimuthal angle, measured along the horizon of the observer at a particular latitude. It seems to be an excessively inaccurate and complicated system when simply a protractor and the single pole star at night, without having to wait for a star to rise or set, or bisection of equally long shadows of the sun on opposite sides of the noon meridian during the day could perform the same function even without a magnetic compass, except in the case of obscuring weather when no method of observing stars would work. In any case, by the method of following stars, many more of the same declination would need to be known in order for a navigator to maintain a course when the assigned one is far above the horizon.
Another way by which angular measurement for direction could arise is from measurement of time.
From division of the year: degrees and sexagesimal angles
From the approximate number of days in the year, the Babylonians divided a circle into three hundred and sixty degrees. It is possible to encounter modern compasses that are graduated with the three hundred and sixty degrees of the circle, with emphasis on the twelve directions at sequential intervals of thirty degrees. In modern astronomy, minutes and seconds of arc are current and in principle could be used for relative direction.
From division of the day: hours
In ancient Egypt, sundials were used in which dawn to dusk was divided into twelve hours. In principle, if the sundial was set level, then the hour marks would point to directions of orientation, though not necessarily at equal angular increments.
Twelve hours on an ancient Egyptian sundial. Image source: https://en.wikipedia.org/wiki/Sundial#/media/File:Ancient-egyptian-sundial.jpg
The Chinese used two dozen named directions on compasses, which came about from an astronomical system.
Two dozen Chinese compass directions on a Korean sundial. Image source: https://en.wikipedia.org/wiki/Sundial#/media/File:휴대용_앙부일구.jpg
Dozenal directions proposal
The following proposal is to divide the circle of directions only by powers of twelve, first into twelve sectors and then each of the twelve sectors further into twelve, to produce twelve squared directions in total. Divisions into twelve are to be achieved by alternation of division by four and then three. Thus, the first subdivision produces the four cardinal directions and quadrants. The second subdivision trisects these quadrants. These two subdivisions produce the division into twelve sectors.
The method of naming the directions in English is as follows:
Table of Dozenal Compass Directions
Square twelfths are omitted for brevity and expedience. Their names and abbreviations are formed by compounding such that the word "of" appears twice.
Advantages of this proposal include that
References
See also:
Cardinal Directions
Older directional names appear for the four cardinal directions originating from a North and South wind axis and a dawn to dusk axis.
The Twelve Classical Wind Directions
Elaboration and refinement of the cardinal directions with intercardinal directions produced eight directions, then extended to twelve by philosophers. Classically in Greek and later in Latin, the twelve directions were named by winds blowing from those directions. These were:
Wind source direction | Greek | Latin |
North pole | Aparktias | Septentrio |
Eastern Arctic circle | Meses | Aquilo |
Summer solstice sunrise | Kaikias | Caecias |
Equinox sunrise | Apeliotes | Subsolus |
Winter solstice sunrise | Euronotoi | Eurus |
Eastern Antarctic circle | Phoinikias | Euroauster |
South pole | Notos | Auster |
Western Antarctic circle | Libonotos | Austroafricus |
Winter solstice sunset | Lips | Africus |
Equinox sunset | Zephyros | Favonius |
Summer solstice sunset | Argestes | Corus |
Western Arctic circle | Thraskias | Circius |
Adaptation of these wind directions was proposed for the orienteering directions as of magnetic compasses or to be shown on maps. However, while the resulting angles of these directions may be approximately consistent with dozenal division of the circle at the latitudes in which the Mediterranean civilisations sailed, the directions of the rising and setting points at the horizon of a celestial body such as the sun on the ecliptic vary with latitude.
Binary division of directions
More recent compasses from medieval times have been based on successive bisections of the angles between cardinal directions, as for example on portolan maps. The names of the resulting eight principal wind directions were:
Direction | Latinate name |
North | Tramontana |
Northeast | Greco |
East | Levante |
Southeast | Scirocco |
South | Ostro |
Southwest | Libeccio |
West | Ponente |
Northwest | Maestro |
Compass directions by explorers from Iberia may have been influenced by Islamic navigators.
Astronomically derived angular measure of direction
By rising and setting points on the horizon
It was shown in the table above of the twelve classical wind directions how the solar rising and setting points on the horizon could have been used to determine intercardinal directions.
The principle of celestial rising and setting directions could be extended from the sun, which changes during the year, to the fixed stars, which have the same rising and setting points all year round. However, the directions of rising and setting of the fixed stars still vary with latitude and furthermore their declinations alter over generations due to precession, causing the celestial systems which were once used to be now obsolete.
I found it surprising that the binary compass directions were assigned by the Muslims to fixed stars roughly according to their declinations, even though declination is a polar angle, measured between the pole and equator, whereas the compass direction is an azimuthal angle, measured along the horizon of the observer at a particular latitude. It seems to be an excessively inaccurate and complicated system when simply a protractor and the single pole star at night, without having to wait for a star to rise or set, or bisection of equally long shadows of the sun on opposite sides of the noon meridian during the day could perform the same function even without a magnetic compass, except in the case of obscuring weather when no method of observing stars would work. In any case, by the method of following stars, many more of the same declination would need to be known in order for a navigator to maintain a course when the assigned one is far above the horizon.
Another way by which angular measurement for direction could arise is from measurement of time.
From division of the year: degrees and sexagesimal angles
From the approximate number of days in the year, the Babylonians divided a circle into three hundred and sixty degrees. It is possible to encounter modern compasses that are graduated with the three hundred and sixty degrees of the circle, with emphasis on the twelve directions at sequential intervals of thirty degrees. In modern astronomy, minutes and seconds of arc are current and in principle could be used for relative direction.
From division of the day: hours
In ancient Egypt, sundials were used in which dawn to dusk was divided into twelve hours. In principle, if the sundial was set level, then the hour marks would point to directions of orientation, though not necessarily at equal angular increments.
Twelve hours on an ancient Egyptian sundial. Image source: https://en.wikipedia.org/wiki/Sundial#/media/File:Ancient-egyptian-sundial.jpg
The Chinese used two dozen named directions on compasses, which came about from an astronomical system.
Two dozen Chinese compass directions on a Korean sundial. Image source: https://en.wikipedia.org/wiki/Sundial#/media/File:휴대용_앙부일구.jpg
Dozenal directions proposal
The following proposal is to divide the circle of directions only by powers of twelve, first into twelve sectors and then each of the twelve sectors further into twelve, to produce twelve squared directions in total. Divisions into twelve are to be achieved by alternation of division by four and then three. Thus, the first subdivision produces the four cardinal directions and quadrants. The second subdivision trisects these quadrants. These two subdivisions produce the division into twelve sectors.
The method of naming the directions in English is as follows:
- The cardinal directions are the same, namely East, North, West, and South.
- The directions resulting from the trisection are named from previous directions by their combination in the form x of y, where y is the angularly closer direction and x is the angularly farther direction, and such that the compound direction is a third of the way from Y to X. The abbreviation for the combination is XoY, where X and Y are the initial letters of the cardinal directions being compounded.
- In the second quartering of directions, those directions that bisect the cardinal directions are named by compounding the names of those cardinal directions in the same way as is customary in the binary scheme.
Table of Dozenal Compass Directions
Angle from East in radians | Direction name | Abbreviation | |||
Quarters | Twelfths | Half twelfths | Quarter Twelfths | ||
0*tau/4 | East | E | |||
tau/④⓪ | East Northeast of East | ENEoE | |||
tau/②⓪ | Northeast of East | NEoE | |||
3*tau/④⓪ | East Northeast | ENE | |||
tau/①⓪ | North of East | NoE | |||
5*tau/④⓪ | East Northeast of Northeast | ENEoNE | |||
3*tau/②⓪ | Northeast | NE | |||
7*tau/④⓪ | North Northeast of Northeast | NNEoNE | |||
2*tau/①⓪ | East of North | EoN | |||
9*tau/④⓪ | North Northeast | NNE | |||
5*tau/②⓪ | Northeast of North | NEoN | |||
⑪*tau/④⓪ | North Northeast of North | NNEoN | |||
tau/4 | North | N | |||
①①*tau/④⓪ | North Northwest of North | NNWoN | |||
7*tau/②⓪ | Northwest of North | NWoN | |||
①③*tau/④⓪ | North Northwest | NNW | |||
4*tau/①⓪ | West of North | WoN | |||
①⑤*tau/④⓪ | North Northwest of Northwest | NNWoNW | |||
9*tau/②⓪ | Northwest | NW | |||
①⑦*tau/④⓪ | West Northwest of Northwest | WNWoNW | |||
5*tau/①⓪ | North of West | NoW | |||
①⑨*tau/④⓪ | West Northwest | WNW | |||
⑪*tau/②⓪ | Northwest of West | NWoW | |||
①⑪*tau/④⓪ | West Northwest of West | WNWoW | |||
2*tau/4 | West | W | |||
②①*tau/④⓪ | West Southwest of West | WSWoW | |||
①①*tau/②⓪ | Southwest of West | SWoW | |||
②③*tau/④⓪ | West Southwest | WSW | |||
7*tau/①⓪ | South of West | SoW | |||
②⑤*tau/④⓪ | West Southwest of Southwest | WSWoSW | |||
①③*tau/②⓪ | Southwest | SW | |||
②⑦*tau/④⓪ | South Southwest of Southwest | SSWoSW | |||
8*tau/①⓪ | West of South | WoS | |||
②⑨*tau/④⓪ | South Southwest | SSW | |||
①⑤*tau/②⓪ | Southwest of South | SWoS | |||
②⑪*tau/④⓪ | South Southwest of South | SSWoS | |||
3*tau/4 | South | S | |||
③①*tau/④⓪ | South Southeast of South | SSEoS | |||
①⑦*tau/②⓪ | Southeast of South | SEoS | |||
③③*tau/④⓪ | South Southeast | SSE | |||
⑩*tau/①⓪ | East of South | EoS | |||
③⑤*tau/④⓪ | South Southeast of Southeast | SSEoSE | |||
①⑨*tau/②⓪ | Southeast | SE | |||
③⑦*tau/④⓪ | East Southeast of Southeast | ESEoSE | |||
⑪*tau/①⓪ | South of East | SoE | |||
③⑨*tau/④⓪ | East Southeast | ESE | |||
①⑪*tau/②⓪ | Southeast of East | SEoE | |||
③⑪*tau/④⓪ | East Southeast of East | ESEoE |
Square twelfths are omitted for brevity and expedience. Their names and abbreviations are formed by compounding such that the word "of" appears twice.
Advantages of this proposal include that
- it maintains the current binary compound directions unchanged whereby
- bisections are simple compounds of the bisected directions.
References
- https://en.wikipedia.org/wiki/Cardinal_direction
- https://en.wikipedia.org/wiki/Classical_compass_winds
- https://en.wikipedia.org/wiki/Compass_rose
- https://en.wikipedia.org/wiki/Points_of_the_compass
- https://en.wikipedia.org/wiki/Sundial
See also:
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